College - Tier 3
Current CTC - 7,5 LPA (fixed) - Service based MNC
Offer in-hand - 12 LPA (fixed) - Product based MNC (EPAM systems)
Experience - 2.4 Years

How much should I ask. I am thinking of Base Salary - 18 LPA and Bonus - 2LPA.
All rounds went really well, interviewers are impressed.
Should I ask for more?
Please help me out.
I have not done salary negotiation before, Any tips would be helpful.

Update - I asked for 18 LPA in the begining, the HR guy was very rude and unprofessional, he started the disccuion directly by asking for the current CTC and Expected CTC. First I aksed him about their salary range and he siad they don't have salary range they just give 25-30% on current CTC. So he asked me for the expected number. I give his my expected CTC (18 LPA) with some facts and logic based on Market data. But he keep avoidng them said max he can do is match my current in hand offer (12 LPA) with some variable and can offer me 13.5 LPA and after some 5 - 6 mins he started behaving very rude and start shouting that he can only strech it to 14 LPA including variable pay. I calmly asked him for 16 LPA (fixed) which he reply again that's the max they can stretch it (13 fixed + 75k retention bonus) and for that too he has to take approval.
Seriously, that's not what I was expecting from Reliance JIO. Such a bad expereice, wasted the whole week. And most shocking thing is that It's all happening after they asked my expected salary even before the interviews rounds.

[1 Dec] Update: Almost after 3 weeks they came back with offer of 16.5 LPA (~14 LPA fixed + 2.5LPA Retirals and Bonus) .